var snake = new Array;

var board = new Array;

var links = new Array;

var scheduledDirections = new Array;

var numRows = 1;

var numColumns = 1;

var linkComponent = Qt.createComponent("content/Link.qml"); // XXX should resolve relative to script, not component

var cookieComponent = Qt.createComponent("content/Cookie.qml");

var cookie;

var linksToGrow = 0;

var linksToDie = 0;

var waitForCookie = 0;

var growType = 0;

var skullMovementsBeforeDirectionChange = 0;

function rand(n)

{

  return (Math.floor(Math.random() * n));

}

function scheduleDirection(dir)

{

    direction = dir;

    if(scheduledDirections[scheduledDirections.length-1]!=direction)

        scheduledDirections.push(direction);

}

function startNewGame()

{

    if (state == "starting")

        return;

    if (heartbeat.running) {

        endGame();

        startNewGameTimer.running = true;

        return;

    }

    numRows = numRowsAvailable;

    numColumns = numColumnsAvailable;

    board = new Array(numRows * numColumns);

    snake = new Array;

    scheduledDirections = new Array;

    growType = 0;

    skull.z = numRows * numColumns + 1;

    for (var i = 0; i < numRows * numColumns; ++i) {

        if (i < links.length) {

            var link = links[i];

            link.spawned = false;

            link.dying = false;

        } else {

            if(linkComponent.status != Component.Ready) {

                if(linkComponent.status == Component.Error) 

                    console.log(linkComponent.errorString());

                else

                    console.log("Still loading linkComponent");

                continue;//TODO: Better error handling?

            }

            var link = linkComponent.createObject(playfield);

            link.z = numRows * numColumns + 1 - i;

            link.type = i == 0 ? 2 : 0;

            link.spawned = false;

            link.dying = false;

            links.push(link);

        }

    }

    head = links[0];

    snake.push(head);

    head.row = numRows/2 -1;

    head.column = numColumns/2 -1;

    head.spawned = true;

    linksToGrow = 5;

    linksToDie = 0;

    waitForCookie = 5;

    score = 0;

    startHeartbeatTimer.running = true;

    heartbeat.running = true;

}

function endGame()

{

    heartbeat.running = false;

    for(var i in snake)

        snake[i].dying = true;

    if (cookie) {

        cookie.dying = true;

        cookie = 0;

    }

    lastScore = score;

    highScores.saveScore(lastScore);

}

function move() {

    if (!head)

        return;

    var dir = direction;

    if (scheduledDirections.length) {

        dir = scheduledDirections.shift();

    }

    if (state == "starting") {

        var turn = (dir - headDirection);

        head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );

        headDirection = dir;

        return;

    }

    var row = head.row;

    var column = head.column;

    if (dir == 0) {

        row = row - 1;

    } else if (dir == 1) {

        column = column + 1

    } else if (dir == 2) {

        row = row + 1;

    } else if (dir == 3) {

        column = column - 1;

    }

    //validate the new position

    if (row < 0 || row >= numRows

        || column < 0 || column >= numColumns

        || (row == skull.row && column == skull.column)

        || !isFree(row, column)) {

        var turn = (dir - headDirection);

        head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );

        headDirection = dir;

        endGame();

        return;

    }

    var newLink;

    if (linksToGrow > 0) {

        --linksToGrow;

        newLink = links[snake.length];

        newLink.spawned = false;

        newLink.rotation = snake[snake.length-1].rotation;

        newLink.type = growType;

        newLink.dying = false;

        snake.push(newLink);

    } else {

        var lastLink = snake[snake.length-1];

        board[lastLink.row * numColumns + lastLink.column] = Undefined;

    }

    if (waitForCookie > 0) {

        if (--waitForCookie == 0)

            createCookie(cookie? (cookie.value+1) : 1);

    }

    for (var i = snake.length-1; i > 0; --i) {

        snake[i].row = snake[i-1].row;

        snake[i].column = snake[i-1].column;

        snake[i].rotation = snake[i-1].rotation;

    }

    if (newLink) {

        newLink.spawned = true;

    }

    // move the head

    head.row = row;

    head.column = column;

    board[row * numColumns + column] = head;

    var turn = (dir - headDirection);

    head.rotation += turn == -3 ? 1 : (turn == 3 ? -1 : turn );

    headDirection = dir;

    var value = testCookie(row, column);

    if (value > 0) {

        linksToGrow += value;

        score += value;

    }

}

function isFree(row, column)

{

    return board[row * numColumns + column] == Undefined;

}

function isHead(row, column)

{

    return head.column == column && head.row == row;

}

function testCookie(row, column)

{

    if (cookie && !cookie.dying && cookie.row == row && cookie.column == column) {

        var value = cookie.value;

        waitForCookie = value;

        growType = snake[snake.length-1].type == 1 ? 0 : 1;

        cookie.dying = true;

        cookie.z = numRows * numColumns + 2;

        return value;

    }

    return 0;

}

function moveSkull()

{

    if (linksToDie > 0) {

        --linksToDie;

        var link = snake.pop();

        link.dying = true;

        board[link.row * numColumns + link.column] = Undefined;

        if (score > 0)

            --score;

        if (snake.length == 0) {

            endGame();

            return;

        }

    }

    var row = skull.row;

    var column = skull.column;

    if (isHead(row, column)) {

        endGame();

        return;

    }

    row +=  skull.verticalMovement;

    column += skull.horizontalMovement;

    var attempts = 4;

    while (skullMovementsBeforeDirectionChange == 0 || row < 0 || row >= numRows

        || column < 0 || column >= numColumns

        || (!isFree(row, column) && !isHead(row, column))) {

        var d = rand(8);

        skull.verticalMovement = 0;

        skull.horizontalMovement = 0;

        skullMovementsBeforeDirectionChange = rand(20)+1;

        if (d == 0) {

            skull.verticalMovement = -1

        } else if (d == 1) {

            skull.horizontalMovement = -1;

        } else if (d == 2) {

            skull.verticalMovement = 1

        } else if (d == 3){

            skull.horizontalMovement = 1;

        } else if (cookie) {

            var rd = cookie.row - skull.row;

            var rc = cookie.column - skull.column;

            if (Math.abs(rd) > Math.abs(rc)) {

                skull.verticalMovement = rd > 0 ? 1 : -1;

                skullMovementsBeforeDirectionChange = Math.abs(rd);

            } else {

                skull.horizontalMovement= rc > 0 ? 1 : -1;

                skullMovementsBeforeDirectionChange = Math.abs(rc);

            }

        }

        row = skull.row + skull.verticalMovement;

        column = skull.column + skull.horizontalMovement;

        if (--attempts == 0)

            return;

    }

    skull.row = row;

    skull.column = column;

    --skullMovementsBeforeDirectionChange;

    var value = testCookie(row, column);

    if (value > 0)

        linksToDie += value/2;

    if (isHead(row, column))

        endGame();

}

function createCookie(value) {

    if (numRows * numColumns - snake.length < 10)

        return;

    var column = rand(numColumns);

    var row = rand(numRows);

    while (!isFree(row, column)) {

        column++;

        if (column == numColumns) {

            column = 0;

            row++;

            if (row == numRows)

                row = 0;

        }

    }

    if(cookieComponent.status != Component.Ready) {

        if(cookieComponent.status == Component.Error)

            console.log(cookieComponent.errorString());

        else

            console.log("Still loading cookieComponent");

        return;//TODO: Better error handling?

    }

    cookie = cookieComponent.createObject(head.parent);

    cookie.value = value;

    cookie.row = row;

    cookie.column = column;

}